Bacterial vaginosis is considered as a common vaginal disorder in women of reproductive age. Whereas the normal vaginal flora consists of lactobacilli, especially L. crispatus, the disturbed vaginal microflora was mainly characterized in the past by the overgrowth of Gardnerella vaginalis (formerly known as Haemophilus vaginalis) and anaerobic bacteria such as Mobiluncus spp., Mycoplasma hominis and Prevotella spp. More recently, the interest for bacterial vaginosis increased because of reports of adverse sequelae of this disorder, such as preterm birth (Hay P E et al. Brit Med J 1994, 308:295-298), pelvic inflammatory disease (Haggerty C L et al. Clin Infect Dis 2004, 39:990-995) and postpartum endometritis (Watts D H et al. Obstet Gynecol 1990, 75:52-58).
The severity of the consequences of those sequelae asks for an adequate treatment of bacterial vaginosis. In the art, the drug of choice in the treatment of bacterial vaginosis is oral or topical metronidazole, a nitroimidazole derivative, which is considered as the golden standard in the management of non mycotic vaginal infections. Metronidazole is an antiprotozoarian drug, endowed with therapeutic effect in genital protozoarian infections of both sexes, like trichomoniasis, and also on protozoarian infections of gastrointestinal tract, like intestinal amoebiasis due to Giardia lamblia. Metronidazole is also provided of an inhibitory effect on the growth of Gardnerella vaginalis and other bacteria, but is not considered as an antibiotic as it has no effect on the normal flora of lactobacilli. Nifuratel is a nitrofurane derivative and is considered as the alternative to metronidazole, being endowed of similar effect on protozoa (Trichomonas and Giardia lamblia) and on Gardnerella, with no effect on lactobacilli. Thus, metronidazole and nifuratel are both antiprotozoarian drugs, with an inhibitory effect on Gardnerella. 
Recently, it has been put in evidence that a new microorganism, named Atopobium vaginae, is strongly associated with bacterial vaginosis (Verstraelen H et al. Am J Obstet Gynecol 2004, 191:1130-1132) and is likely the cause of failure to metronidazole treatment and of relapses. Atopobium is an anaerobe bacteria never described before, a metronidazole resistant organism, that may account for the antimicrobial resistance (up to 30%) associated with the treatment of bacterial vaginosis with metronidazole (Larsson P G et al. APMIS 2005, 113:305-316). Atopobium vaginae has been described to constitute a consistent part of the bacteria that form an adherent biofilm on the vaginal epithelium even after standard therapy with metronidazole (Swidsinski A, Mendling W et al. Am J Obstet Gynecol 2008; 198:97.e1-97.e6) and has been found in urine and in urinary epithelium of male partners of women with bacterial vaginosis.
It has now surprisingly been found that nifuratel, a drug with an antimicrobial spectrum similar to that of metronidazole, is provided of an inhibitory effect on the growth of strains of Atopobium, that are resistant to metronidazole.